Dell XPS 13 9350 disconnecting from external screen powered via USB C

Some Dell XPS 13 9350 laptop models have a Dell Wireless 1820A 802.11ac WiFi card. This can cause interference with the USB C port (even if the latest Thunderbolt firmware/driver and machine BIOS is installed). The resolution to this is to view the properties of the wireless card and turn down the power output to 25%. You can bump it up to 50% and see if the flickering/disconnecting happens again – if it does, turn down for what to 25% again. (hat-tip to “drewnick” on Reddit and this StWong blog link.)